diff --git a/IPython/zmq/newserialized.py b/IPython/zmq/newserialized.py
index 07577a7..a534d2c 100644
--- a/IPython/zmq/newserialized.py
+++ b/IPython/zmq/newserialized.py
@@ -119,7 +119,7 @@ class SerializeIt(object):
         elif self.typeDescriptor in ('bytes', 'buffer'):
             self.data = self.obj
         elif self.typeDescriptor == 'pickle':
-            self.data = pickle.dumps(self.obj, 2)
+            self.data = pickle.dumps(self.obj, -1)
         else:
             raise SerializationError("Really wierd serialization error.")
         del self.obj
diff --git a/IPython/zmq/parallel/streamsession.py b/IPython/zmq/parallel/streamsession.py
index c01e300..d98b5fe 100644
--- a/IPython/zmq/parallel/streamsession.py
+++ b/IPython/zmq/parallel/streamsession.py
@@ -160,7 +160,7 @@ def serialize_object(obj, threshold=64e-6):
         clist = canSequence(obj)
         slist = map(serialize, clist)
         for s in slist:
-            if s.getDataSize() > threshold:
+            if s.typeDescriptor in ('buffer', 'ndarray') or s.getDataSize() > threshold:
                 databuffers.append(s.getData())
                 s.data = None
         return pickle.dumps(slist,-1), databuffers